There is currently great interest in hydrogen as an emission-free fuel for automobiles to both increase fuel economy and decrease vehicle emissions [1]-[3]. It is expected that hydrogen can become a major energy supply in many applications, including transportation, central and distributed electric power, portable power, and combined heat and power for buildings and industrial processes [2], [3]. Because hydrogen gas is extremely reactive with oxygen and has low ignition energy, it is prone to spontaneous flammable ignition. It is therefore critically important that robust and fast hydrogen gas detection technologies be available to ensure safe handling [1]-[3].